The Trial of Galileo: Selected Letters
Galileo to Kepler / Kepler to Galileo  (1597)
Galileo to Kepler (August 19, 1610)
Galileo to Castelli  (December 21, 1613)
Father Lorini to Cardinal Sgondrati (February 7, 1615)
Piero Dini to Galileo (March 3, 1615)
Cardinal Bellarmine to Father Foscarini (April 4, 1615)
Galileo to Piero Dini (May, 1615)
Galileo to Grand Duchess Christina (1615)
Galileo to Tuscan Secretary of State (January 23, 1616)
Cardinal Bellarmine to Galileo (May 26, 1616)
Galileo's Doctors (December 17, 1632)
Maria Celeste (Galileo's daughter) to Galileo  (April 20, 1633)
Commissary-General Firenzuola to Cardinal Francesco Barberini  (April 28, 1633)
Galileo to Diodati (July 23, 1634)
A large collection of letters from Maria Celeste, Galileo's duaghter, to her father is posted online.  The collection is accessible at The Galileo Project, a  website of Rice University. 

To see the letters of Maria Celeste, click here:Letters from Galileo's Daughter

Galileo Trial Homepage